Drop-on-demand ink jet printers use thermal energy to produce a vapor bubble in an ink-filled chamber to expel a droplet. A thermal energy generator or heating element, usually a resistor, is located in the chamber on a heater chip near a discharge nozzle. A plurality of chambers, each provided with a single heating element, are provided in the printer's printhead. The printhead typically comprises the heater chip and a nozzle plate having a plurality of the discharge nozzles formed therein. The printhead forms part of an ink jet print cartridge which also comprises an ink-filled container.
A plurality of dots comprising a swath of printed data are printed as the ink jet print cartridge makes a single scan across a print medium, such as a sheet of paper. The data swath has a given length and width. The length of the data swath, which extends transversely to the scan direction, is determined by the size of the heater chip.
Printer manufacturers are constantly searching for techniques which may be used to improve printing speed. One possible solution involves using larger heater chips. Larger heater chips, however, are costly to manufacture. Heater chips are typically formed on a silicon wafer having a generally circular shape. As the normally rectangular heater chips get larger, less of the silicon wafer can be utilized in making heater chips. Further, as heater chip size increases, the likelihood that a chip will have a defective heating element, conductor or other element formed thereon also increases. Thus, manufacturing yields decrease as heater chip size increases.
Accordingly, there is a need for an improved printhead or printhead assembly which allows for increased printing speed yet is capable of being manufactured in an economical manner.